The field is of type Object or other reference type, defaultValue is not nulla null reference (Nothing in Visual Basic), and the value cannot be assigned to the reference type.

Remarks

defaultValue is restricted to the following types: Boolean, SByte, Int16, Int32, Int64, Byte, UInt16, UInt32, UInt64, Single, Double, DateTime, Char, String, and Enum. If the field type is a reference type, CLS compliance requires defaultValue to be nulla null reference (Nothing in Visual Basic). However, starting with Silverlight 4, defaultValue can be non-null for a reference type as long as the value can be assigned to that reference type. For example, an Int32 value can be assigned to a field of type Object. This is not CLS-compliant, but it can be useful in interop scenarios.